Devices for locking the draw hooks in dobbies



April 5, 1955 H. H. STUBLI DEVICES FOR LOCKING THE DRAW HOOKS IN DOBBIES United States Patent O DEVICES FOR LOCKING THE DRAW HOOKS IN DOBBIES Heinrich Hugo Stubli, Horgen, Switzerland, assignor to Gebr. Stubli & Co., Horgen, Zurich, Switzerland, a company of Switzerland Application October 15, 1953, Serial No. 386,314 Claims priority, application Switzerland January 26, 1953 1 Claim. (Cl. 139-71) The present invention relates to a device for locking the draw hooks in dobbies.

In most dobbies the draw hooks are so arranged in relation to the draw knives that they drop on to the draw knives by a free fall, these hooks including an acute angle, while the cross section of the knives exhibits a congruent angle, to which the hooks are attached. This does not give rise to any tendency that the hooks should automatically jump off the knife during the running of the machine. In dobbies in which the hooks have to be brought from below to the draw knives to be attached thereon or where the hooks include a right angle and the knives also are of a rectangular cross section, it is possible for the hooks to slip ot the knives. In such machines it is necessary to secure the hooks so that they do not accidentally jump off the knife.

According to the present invention the hooks are rockably mounted in the balance levers, and to each of these hooks is allocated a spring which tends to press it against the knife to which it has been attached in accordance with the pattern card, the spring being rockably held on the hooks and on the balance levers that carries them, in such a way that when the hooks are brought to engage one of the knives it is rocked in such a manner that the spring pressure is always operative on that side on which the hook is engaged.

One constructional example of a device according to the invention as applied to a double-lift positive motion dobby is illustrated in the accompanying drawing.

This machine comprises an upper pair of knives 1 and 2, and a lower pair of knives 3 and 4. With the upper knives 1 and 2 there co-operate hooks 5, and, with the ICC lower pair of knives 3 and 4, hooks 6. The hooks 5 and 6 are rockably mounted on balance levers 7. The fulcrum 8 of the upper hook 5 is located at the height of the upper knives, and the hooks 5 are pressed from below against the knives 1 or 2. The fulcrum 9 of the lower hooks is located at the level of the lower knives 3 and 4, and the lower hooks 6 are pressed from above against the lower knives 3 and 4. To diminish the clearance required between the hooks and the knives, the hooks are rectangular, as is also the cross section of the knives. The upper hooks and the lower hooks have radially ex tending arms 10 and 11 respectively, which are directed towards the middle of the balance lever 7. To a pin 12 on the arm 10 and to a pin 13 on the arm 11 is attached in each case one outstanding arm of a helical torsion spring 14 or 15, the other arm of which bears on a pin 16 or 17 secured to the balance lever. The position of the pins 16 and 17 on the balance lever 7 is so selected that the hooks, in their end positions, that is to say, when they have been brought into engagement with one or the other of the associated knives, are pressed by the springs 14 and 15 against the knives, the springs 14 and l5, when the hooks are rocked, being rocked about the pins 16 or 17 in such a way that the spring pressure is always operative upon the side of the pin 16 or 17 upon which the hook is engaged.

The ends of the arms of the helical torsion springs may advantageously be constructed as laterally open hooks, so that they can be simply slipped on to these pins 12, 13, 16 and 17, thereby facilitating an exchanging of the springs.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

A device for locking draw hooks to the knives engaging therewith in dobbies, comprising: a balance lever, draw hooks rockably mounted on the balance lever, and springs rockably mounted by one end on the balance lever, each such spring being rockably connected by its other end with one of the draw hooks to press it against a knife engaging therewith, the connection between the springs, the balance lever and the draw hooks being such that whenever a hook engages with one of the knives the spring pressure is always operative in such a direction as to maintain such engagement.

No references cited. 

